Transmission clutch controls can generally be characterized as either open-loop or closed-loop. In open-loop controls, the clutch pressures during shifting are carried out according to a predefined schedule as a function of time and some other powertrain parameter, such as engine throttle or an estimate of the transmission input torque; see, for example, the U.S. Pat. No. to Downs et al. 4,653,350, issued March 31, 1987, and assigned to the assignee of the present invention. In closed-loop controls, the clutch pressures during shifting are developed in relation to the error or difference between desired and actual values of a transmission parameter, such as input speed, input acceleration or output torque; see, for example, the U.S. Pat. Nos. to Sanders et al. 3,754,482, issued Aug. 28, 1973, and Lockhart et al. 4,724,723, issued Feb. 16, 1988, both of which are assigned to the assignee of the present invention.